Abstract. This research team recently published the first quantitative proteomic analysis of a devel- oping embryo (Sci Rep. 2014; 4: 4365. PMID: 24626130). We studied single Xenopus laevis embryos at six stages of development. We initially quantified the expression change of 4,000 proteins across at least four stages of development; reanalysis of the data with an improved genomic database has extended our identifications by 50%. Data have been made available to the community on the Scien- tific Reports web site, at Xenbase, and at PeptideAtlas. We will extend our initial study by quantitatively monitoring the expression and phosphorylation status of proteins isolated from single Xenopus oocytes, eggs, and blastomeres. Quantitative protein expression changes will also be measured from cryosections perpendicular to developmental axes to identify patterning gradients, along a selected cell lineage, from an explant of that lineage, and in oocytes following nuclear transplantation. The results of these studies will be an unprecedented resource to the Xenopus community by providing detailed data on the evolution of protein expression during development, and chromatin reorganization in embryos and following nuclear transplantation. We will work with Xenbase, PeptideAtlas, and VectorBase to disseminate our results as widely as possible.